To comply with the progress of semiconductor integrated circuits toward higher degrees of integration, a technology of processing to smaller feature sizes is needed. In the microfabrication technology of semiconductor devices of the next generation based on ULK/copper interconnection, a material-friendly processing technique is needed in order to make effective use of materials having insufficient chemical and physical strengths. In particular, the technique of processing porous silicon base low-dielectric materials having a relative permittivity of up to 2.7 requires engineers to review and tailor the steps in the overall process including cleaning, etching and CMP and to look for novel materials suited therefor.
For example, in connection with the dual-damascene manufacture by via-first process, Richard Spear et al. proposed spin-on-glass materials as the anti-reflective coating/filling material in JP-A 2003-502449, U.S. Pat. No. 6,268,457 and U.S. Pat. No. 6,506,497. Also a spin-on-glass material having no anti-reflective effect was proposed as the low-dielectric constant film-forming filling material. The spin-on-glass materials have a high structural similarity to the silica base low-dielectric constant film and raise no problem in pattern shape during fluorocarbon gas dry etching, but fail to establish a selectivity during wet etching and are difficult to control the shape after stripping. On the other hand, when organic materials are used as the filling material, they tend to generate shape abnormalities in proximity to the interface between the organic film and the low-dielectric constant film during fluorocarbon gas dry etching for low-dielectric constant material processing after the oxygen gas dry etching step.